Many devices are known for preventing a firearm from being used by an unauthorized person, such as children or other non-owners. For example, U.S. Pat. No. 6,357,156 describes a system for use with an electronic firearm. The system has a fingerprint sensor used to compare the sensed fingerprint pattern of a would-be shooter with an authorized user's fingerprint pattern stored in an identification circuit. The identification circuit communicates with an electrical interface for transmitting an authorization signal to activate the firearm if the sensed fingerprint pattern substantially matches the authorized user's fingerprint pattern. The system is powered by DC batteries.
U.S. Pat. No. 6,711,843 describes an electronic firearm that includes a barrel assembly and a handle assembly coupled to the barrel assembly. The handle assembly includes a grip portion defining a cavity and one or more openings disposed generally at a rear side of the grip portion. A biometric sensing device is disposed within the cavity and aligned with the openings of the grip portion for scanning the skin of a portion of the user's hand to determine whether the user is authorized to discharge the electronic firearm.
U.S. Pat. No. 4,970,819 describes a system in which actuation of the firing mechanism of a firearm is prevented until grip pattern sensing means on the handgrip of the firearm supply to a microprocessor signals corresponding to a grip pattern stored in a programmed simulated neural network memory.
In all of the known systems of the prior art, the firearm is normally inoperable (that is, cannot be used to fire a projectile) unless the system recognizes the shooter as an authorized shooter. In other words, something blocks or interferes with the firing mechanism and that something moves away to allow the firing mechanism to work only upon recognition of the shooter as an authorized shooter.